1. Field of the Invention
This invention relates to the cleaning of electric circuits. More specifically, the invention relates to a cleaning fluid and method for removing metal salts and contaminants from conductor surfaces in electrical circuits.
Electricians have ordinary skill in the art.
2. Description of Related Art
In commercial and industrial applications, electric circuits and systems are formed by connecting electrically conducting ends of wires to connectors. A connection can be made to equipment, to a different wire, or to a bus. In general, wires and connectors are made of copper or aluminum, but they can also be made of alloys of copper or aluminum. Connectors can be made of other conductors such as steel, or other metals and alloys.
Over a period of time the electrical circuit can lose efficiency due to corrosion and contamination at the various connections. The environment surrounding a circuit influences the length of time that passes before the loss of efficiency in an electric circuit becomes noticeable. In high salinity areas, such as areas close to an ocean or a sea, and in high humidity areas, it does not take much time to notice a loss of efficiency in an electrical circuit.
Loss of efficiency in a circuit is often caused by corrosion, which is the formation of metal salts and the presence of other contaminants at a connection. Metal salts are very poor conductors or non-conductors. Metal salts on a conductor at a connection act like a resistor and reduce the flow of electricity through the connection. In extreme cases, corrosion may prevent the flow of electricity through a connection, causing an open circuit. Corrosion at a connection may cause heat generation because of increased impedance in the circuit, and can lead to fire. A significant loss of efficiency in a circuit or system due to corrosion requires that the circuit or system be reworked.
There are five primary methods for reworking electrical circuits and systems in commercial and industrial applications. The first method is a complete rewiring of an electrical system or circuit with all new electrical equipment and new lines or conductors. The disadvantage of this method is that it is extremely costly; much more costly than the installation of the original electrical system.
The second method is to disconnect a wire from a connector, cut off a corroded section of the wire, strip a section of the insulation so the wire can be reconnected to the connector, and reconnect the wire to the connector. This method is limited by the length of the wire originally installed.
The third method is to disconnect a wire from a connector and dip the wire in acid to remove corrosion from the wire. The wire would then be reconnected to the connector. This method increases the reliability of an electrical system; however, it costs a significant amount of electrical energy because it reduces the wire size, therefore acting as a resistor in line. For those lines that have heavy loads, this may be critical and actually cause the lines to fall below the national electrical code on size of wires relating to load.
The fourth method is to loosen the conductors or wires from the connectors and to abrade the conductors or wires with a steel brush or sandpaper to remove corrosion. The conductors or wires are then reconnected to the connectors. This method produces a more reliable electrical circuit and is generally used where reliability is extremely important; however, the method leaves abrasion marks on the conductor. The abrasion marks create more conductor surface area, and corrosion reoccurs more rapidly, especially in a humid or high-salinity environment.
The fifth method is one that is used on high voltage power lines. Calcium salts are sprayed on the conductors to remove and replace oxidized copper or aluminum salts and other corrosion compounds that exist at connections. The disadvantage of this method is that the spray promotes electrolysis between dissimilar metals, and upon drying, the spray leaves large mounts of the calcium based compounds or salts as residue. These residues are non-conductors in dry form. Furthermore, when this method is used, it must be repeated very frequently.
In the manufacture of copper and aluminum wiring, petroleum based oils are left on the wires to prevent oxidation of the wire. These oils are an impediment to the flow of electricity when the wire is connected to an electrical circuit. The impedance can generate heat, which can cause a fire since petroleum based oils are generally flammable.
There are many different cleaning fluids. One type of cleaning fluid uses terpenes as a solvating agent. U.S. Pat. No. 5,238,504, issued to Henry, discloses a terpene and ketone blend. This cleaning solution is a non-aqueous solution which can be used to clean electrical contacts.
U.S. Pat. No. 5,277,836, issued to Peters, discloses a cleaning compound which uses a terpene, a polyalkoxylated alcohol, and water. The compositions have improved grease cutting and rust inhibiting abilities. The composition has a terpene concentration of at least 10% by weight, so that the compositions have good grease cutting abilities. U.S. Pat. No. 5,190,679, issued to McDonald, discloses an aqueous loosener composition for removing cable from a conduit. The composition includes a lubricating agent; a solvating agent, such as a terpene; and water. Because the solvating agent is used to loosen "frozen" cables from a conduit wall, the solvating agents are present in high concentrations. At high concentrations, aqueous terpene solutions will corrode aluminum and copper conductors.